FILTER INSULATED IN SELECTIVE MANNER Russian patent published in 1997 - IPC

FIELD: oil and gas well drilling. SUBSTANCE: device has base member of cylindrical shape as a whole. The member has holes and filtering jacket. The jacket is made in the form of sealing members. The sealing members are placed in lengthwise direction on outer surface of the base member. Wire is wrapped on sealing members. The wire together with base member outer surface form annular cavity. This cavity is segregated by sealing members into lengthwise passages. Cross sections of these passages are cut with annular sealing members. Th filtering jacket itself is made in the form of a set of self-contained sections. The sections are interconnected. As this takes place, the sealing members are placed on ends of the sections and are connected to the base member by welding. EFFECT: higher reliability of the filter. 9 cl, 6 dwg